Simulation of gas phase reactions for microcrystalline silicon films fabricated by PECVD

We present a numerical gas phase reaction model for hydrogenated microcrystalline silicon(μc-Si:H) films from SiH4 and H2 gas mixtures with plasma enhanced chemical vapor deposition(PECVD).Under the typical μc-Si:H deposition conditions,the concentrations of the species in the plasma are calculated and the effects of silane fraction(SF=[SiH4]/[H2+SiH4]) are investigated.The results show that SiH3 is the key precursor for μc-Si:H films growth,and other neutral radicals,such as Si2H5,Si2H4 and SiH2,may play some roles in the film deposition.With the silane fraction increasing,the precursor concentration increases,but H atom concentration decreases rapidly,which results in the lower H/SiH3 ratio.